Focus: the exact location under the earth's crust where the rock breaks from stress, triggering an earthquake Epicenter: point that is on the earth's surface, directly above the focus Seismic Waves: vibrations moving with energy caused by an earthquake P waves: seismic waves that compress/expand the ground S waves: seismic waves that make the ground shake violently, vibrating in all directions Surface Waves: slowest of seismic waves, but causes most damage Seismograph: records the movement in the ground made by seismic waves Magnitude: the measurement for an earthquake's strength Mercalli Scale: machine that rates earthquake's intensity Richter Scale: machine that rates size of seismic waves Moment Magnitude Scale: machine that estimates all the energy that was released when an earthquake occured
Outline
Measuring earthquakes
Seismic Waves = Energy of the Earth
Primary Waves
The fastest of the waves
These waves stretch and compress the ground
They make the ground move forward and back only
Secondary Waves
Comes after primary waves
Makes the ground move up and down, left to right
This type of wave cannot go through liquids
Surface Waves
The slowest of the waves
But, it is the most violent wave of the waves
Detecting Seismic Waves
Measuring Earthquakes
Mercalli Scale
The scale which is measured how much damage or effects affect the area
This scale is not accurate because different areas can have different damages
Richter Scale
The Richter Scale was used for 50 years
It needed a special kind of seismograph
It was not accurate because it could not defer large or distant earthquakes
Moment Magnitude Scale
This scale is the most accurate
This scale uses more accurate seismographs, electric ones
Table of Contents
Chapter 2.2
Vocabulary
Focus: the exact location under the earth's crust where the rock breaks from stress, triggering an earthquake
Epicenter: point that is on the earth's surface, directly above the focus
Seismic Waves: vibrations moving with energy caused by an earthquake
P waves: seismic waves that compress/expand the ground
S waves: seismic waves that make the ground shake violently, vibrating in all directions
Surface Waves: slowest of seismic waves, but causes most damage
Seismograph: records the movement in the ground made by seismic waves
Magnitude: the measurement for an earthquake's strength
Mercalli Scale: machine that rates earthquake's intensity
Richter Scale: machine that rates size of seismic waves
Moment Magnitude Scale: machine that estimates all the energy that was released when an earthquake occured
Outline
Measuring earthquakes
Diagram 2-2